6. Brock Lesnar
When Brock Lesnar suddenly told Vince McMahon in early 2004 that he was quitting the WWE, the chairman was severely annoyed. The company had put a ton of faith in Lesnar. They invested heavily in the star in his debut year, having him dominate on route to a WWE title win at Summerslam 2002. By pinning The Rock, 25 year old Lesnar became the youngest WWE champion in history. It was a huge honour, and Lesnar would go on to further dominance as the "face of the company" in 2003. As 2004's Wrestlemania 20 rolled around, Lesnar was one of WWE's biggest assets. The problem was that Lesnar didn't enjoy the WWE lifestyle, and having pushed Lesnar as a main event act so quickly 'The Beast' had become a millionaire and had no real reason to continue enduring something he hated. Lesnar told Vince he wanted out, and there was nothing Vince could do about it. McMahon was beyond frustrated. The Lesnar situation ruined one of Wrestlemania 20's marquee matches (Lesnar vs Goldberg), and also severely hurt the Smackdown roster which was losing Kurt Angle out injured. Straight away, Vince went about doing the one thing he could do - expunging Lesnar from WWE history. The Wrestlemania 19 main event championship match with Angle would now no longer be mentioned, and in a knee jerk reaction Vince had 24 year old Randy Orton pin Chris Benoit at Summerslam 2004 to become the new youngest champion in WWE history. Lesnar was never mentioned on WWE TV again for the rest of that decade. If it were not for Brock becoming a huge star in UFC, he would probably have never had his historical legacy restored. However, Vince saw money to be made as Brock did 1 million pay per view buys for UFC - all of a sudden everyone was friends again and Lesnar is now back on very good terms with Vinnie Mac.